1. Field of the Invention
The invention relates to a method of producing implanted areas on a substrate.
2. Prior Art
Some components in a semiconductor technology require a substrate, such as a silicon semiconductor substrate, which has a periodic doping pattern. For example, German Offenegungsschrift No. 2,049,684 discloses a laser diode comprised of a semiconductor having areas or zones of different dopant concentration so that the spacing of such zones is between a 10- multiple and a 500- multiple of the lattice constant of the semiconductor and thus the dopant zone dimensions are in a range of 1 nm to 1 .mu.m. Known methods of producing such periodic dopant patterns having dimensions above 1 .mu.m generally utilize photo-lithographic masking techniques. For dopant patterns where the dimensions of an individual dopant area is less than 1 .mu.m to about 100 nm, electron or ion irradiation techniques are utilized whereby an ion or an electron beam is deflected or focused via an electrooptical means and is guided to select areas on a substrate. However, when dopant areas having a dimension less than about 10 .mu.m are required, ion-beams are unsuitable for producing such small areas because it is difficult to obtain a high current ion beam having a diameter smaller than 10 .mu.m. A greater concentration of an ion beam may be achieved with high energy ions, however, such ion beam causes such a large radiation damage in the irradiated substrate that no useful component can be attained from a so-damaged not annealed semiconductor.